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       # TANDY/RADIO SHACK
       
          RS-232 UPGRADE BOARD
       
          Card Type               Serial card                            
          Chip Set                Unidentified                           
          Maximum Onboard Memory  Unidentified                           
          I/O Options             Serial port                            
          Hard Drives supported   None                                   
          Floppy drives supported None                                   
          Data Bus                SBus                                   
          Card Size               Half-length, full-height card          
       
   IMG IMG 1
          
       
          +------------------------------------------------------------+
          |                        CONNECTIONS                         |
          |------------------------------------------------------------|
          |       Function        | Label |      Function      | Label |
          |-----------------------+-------+--------------------+-------|
          | DB-25 serial port     |  CN1  | Sbus interface     |  CN2  |
          +------------------------------------------------------------+
       
          +------------------------------------------------------------+
          |          BASE I/O ADDRESS AND INTERRUPT SELECTION          |
          |------------------------------------------------------------|
          |   Address    |  IRQ  |  SW1/1  |  SW1/2  | SW1/3  | SW1/4  |
          |--------------+-------+---------+---------+--------+--------|
          | COM1 (3F8h)  |   4   |   Off   |   Off   |  Off   |   On   |
          |--------------+-------+---------+---------+--------+--------|
          | COM2 (2F8h)  |   3   |   Off   |   On    |  Off   |   On   |
          |--------------+-------+---------+---------+--------+--------|
          | COM3 (3E8h)  |   4   |   On    |   Off   |  Off   |   On   |
          |--------------+-------+---------+---------+--------+--------|
          | COM3 (3E8h)  |   2   |   On    |   Off   |   On   |   On   |
          |--------------+-------+---------+---------+--------+--------|
          | COM4 (2F8h)  |   3   |   On    |   On    |  Off   |   On   |
          |--------------+-------+---------+---------+--------+--------|
          | COM4 (2F8h)  |   5   |   On    |   On    |   On   |   On   |
          +------------------------------------------------------------+